Constant-current system.



PATENTED JUNE 13. 1905.

M. 0. TROY.

CONSTANT CURRENT SYSTEM.

l nventor: Matth sw Ofl'roy, ywj fg APPLICATION FILED DEO.12, 1903.

Witnesses:

Patented June 13, 1905.

UNITED STATES PATENT OFFICE.

MATTHEIV O. TROY, OF SCHENECTADY, NEW YORK, ASSIGNOR TO GEN- ERALELECTRIC COMPANY, A CORPORATION OF NEIV YORK.

CONSTANT-CURRENT SYSTEM.

SPECIFICATION forming part of Letters Patent No. 752,091, dated June 13,1905.

Application filed December 12,1903. Serial No. 184,893.

To 0.7/7, whom, it Timon 0011007 11,:

Be it known that I, MATTHEW O. Tnor, a i

citizen of the United States, residing at Schenectady, county ofSchenectady, State of New York, have invented certain new and usefulImprovements in Constant-Current Systems, of which the following is aspecification.

Constant-current transformers or reactive coils as usually constructedare provided with relatively movable coils which perform theirregulating functions by automatically adjusting their relative distancesapart. \Vhen out of circuit, the coils of these devices lie closetogether, but when in normal operation they 5 are separated from eachother by distances varying inversely with the amount of load. Instarting up apparatus of this type the coils being at that time closetogether possess comparatively low reactance, and therefore draw fromthe mains or supply-circuit a heavy starting-current. The rush ofcurrent which takes place causes a more or less violent separation ofthe coils, and a consequent strain upon the apparatus and possibleinjury thereto.

5 My invention provides means whereby apparatus of the type mentionedmay be started smoothly and without drawing from the mains an excessivestarting-current. The apparatus which I employ is, moreover, espe- 3cially arranged, so that the transformer or other device may be startedfrom any point either near to or distant from the transformer and is ofsuch character as not to require the presence of an attendant tosupervise the action of the transformer.

My invention, therefore, is particularly suitable for controllingtransformers or similar devices located at a substationor other pointdistant from the central station. An

4 arrangement for thus controlling a transformer located at a substationby means operated at the generating-station is represented, mainly indiagram, in the drawing. The

features of novelty possessed by such an arrangement will be pointed outwith particularity in the appended claims.

In the drawing, the device to be controlled is represented by way ofillustration as a constant-current transformer, having a core 1 of theusual form provided with relatively mov- 5 able coils 2 and 3. The coil.2, which in this case is a secondary, is fixed in position and isconnected to a series consumption-circuit L, supplying lights or othertranslating devices, such as 5. The cooperating primary coil 3 ismounted so as to be movable relatively to the secondary 2 and to thisend is carried by one end of a lever 6, pivoted upon some suitablesupport, as 7. The opposite end of the lever has a counterweight 8,which balances part but not all of the weight of the movable coil 3. Ittherefore follows that when no current is flowing in the apparatus themovable coil rests upon the fixed coil.

For supplying current to the transformer 5 any suitable constantpotential source of alternating current may be employed. In thearrangement illustrated in the drawing I have represented for thispurpose a source of three-phase alternating currentindicated con- 7ventionally by three collector-rings 9, having corresponding brushes 1Obearing thereon. From these brushes extend leads which connect with thethree-phase mains 11, 12, and 13. The constant-current transformer isfed 7 5 from one of the three phases of this supply system and for thispurpose is shown as having its primary 3 connected through leads 14 and15, of indefinite length, to the two mains 11 and 13 of the three-phasesystem.

The, main 11 is arranged so that it may be connected by a switch 16 withone or the other of thetwo three-phase leads 17 and 18. \Vhen shiftedfrom lead 17 to the lead 18, the main 11 is, in effect, folded over ontothe main 13, 5 and the primary 3 is therefore short-circuited uponitself and put out of circuit. Under these conditions all thetranslating devices are fed from one and the same phase of the system.This condition of affairs may exist, for 9 example, in the day-time whenthe constantcurrent transformer is not required for use and when thedemand for incandescent lights is small. hen night-time comes, theswitch 16 may be thrown, so as to connect the main 11 with the lead 17.This throws the primary of the transformer across one phase of thesource of current-supply and distributes the incandescent lamp or otherload 19 and 20 across the other two phases. Current then flows throughthe primary of the transformer and the coils under the influence of therepulsive action of the currents therein commence to separate. Therelative movement of the coils is, however, rendered gradual and easy bymeans of a resistance or other currentlimiting device 21, placed inseries with the primary 3. This resistance limits the flow of current tosuch an extent as to prevent too abrupt movement of the primary 3. Assoon, however, as current commences to flow in the primary a solenoid 22in series with the primary is energized. This solenoid is provided witha core 23, carrying a short-circuiting device 24, which by engaging twofixed contacts 25 and 26 closes a short circuit around the resistance21, and thus cuts the same out of circuit. The core 23, which operatesthis shortcircuiting device, is rendered slow in action by means of adash-pot 27.

When the constant-current transformer is first connected in circuit, theresistance 21 interferes with the free passage of current to thetransformer long enough to allow the coils of the transformersto assumetheir working position, after which the resistance is cut out by theshort-circuiting device and the transformer operates as usual.

What I claim as new, and desire to secure by Letters Patent of theUnited States, is

1. The combination of a constant-current device having relativelymovable coils, a resistance in series with one of said coils, and aslow-acting short-circuiting device for the resistance controlled bycurrent flowing to said constant-current device.

2. The combination of a constant-current device having relativelymovable coils, means external to the device for limiting the flowing ofcurrent thereto when the device is first put in circuit, andautomatically-operated means for eliminating the effect of thecurrent-limiting means.

3. In a device for the remote control of constant-current transformersor the like, the combination of resistance in series with the primary ofthe transformer, short-circuiting contacts for the resistance, asolenoid in series with said resistance, a core controlled by thesolenoid for operating said short-circuiting contacts, and means forcausing a yielding resistance to movement of said core.

4:. The combination of constant-current apparatus having relativelymovable parts, a supply-circuit therefor, a resistance or similar devicefor limiting the initial flow of current to said apparatus when firstconnected into circuit, and means controlled by said current for cuttingthe current-limiting means out of circuit.

5. The combination of a multiphase-supply system, means fordisconnecting one main of the system and connecting it to another main,and constant-current apparatus connected betweensaid mains. I

In witness whereof I have hereunto set my hand this 10th day ofDecember, 1903.

MATTHEW O. TROY.

Witnesses:

BENJAMIN B. HULL, HELEN ORFORD.

